The difference between .js, .cjs, and .mjs file extensions

These three file extensions are used for JavaScript's module system, and each has a specific practical role:

1. .js:

• Default file format: .js extension is the common and common format of JavaScript files.

• is used according to context:

  If your project supports CommonJS (CJS), the .js files work as CommonJS.
  When using ES Modules (ESM), .js files can act as ESM.

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• 2. .cjs:

CommonJS modules are used for:

• This extension specifies that the file will act as a CommonJS module.

Backward Compatibility:

Older versions of Node.js had CommonJS as the default module system. .cjs makes sure it's using that module system.

3. .mjs:

ES Modules (ESM) are used for:

The
• .mjs extension ensures that the file will act as an ESM module.

  Modern JavaScript Standard:

It provides new standard module support in Node.js' module system.
.mjs file is mandatory to use ESM's syntax such as import and export.

When to use an extension?

If you need older CommonJS modules, use .cjs.
To use the Modern ESM module, use .mjs.
You can use .js to be context sensitive, but be careful with Node.js configuration.

Conclusion:

• New project: focus on ESM and use .mjs.
• Old or mixed projects: Use modules with .cjs and .mjs separate file extensions.
• Avoid Confusion: If using .js, define the type of package.json properly.

Adding this information to your post will show more professionalism in project management. ?

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